Method of recovering oil



@dfi 1931- c. T. HARDING ET AL 1,826,349

METHOD OF RECOVERING OIL Filed Oct. 24, 1929 23 I EXTRACTION TOWER PALM ou STILL.

mt Z2 ZECOVEEED PALM EEsmuE T [*1 2 SEWTTLJNG i ANK\- l5 JANc-;EE

EXTRACTION STILL T STORAGE TANK .Z, J @3: .5 .J

C Q 4 PUMP PUMP jmewr: .CZARKET HA Runs Jaw/04 C, WHETZEL- Patented Oct. 6, 1931 UNITED STATES PATENT OFFICE CLARKE "r. HARDING, or BATON ROUGE, LouIsI'ANA, AND JosnuA awnnrznn, or rrrrsnu'aen, rENNsYLVANIA, ASSIGNORS 'ro AMERICAN sneer AND TIN PLATE oomrANY, or PITTSBURGH, PENNSYLVANIA, A CORPORATION or NEW JERSEY imrnon or-R'Ecomme OIL Application filed October 24, 1929. Serial No. 402,145.

This invention relates to the recovery of commercially pure palm oil from used or refuse tin pot oil which is removed from the tin plates after tinning and also removed from 5. the tin pots after excessive use.

In coating sheets or plates with tin, the sheets are first passed through a body of flux, then through the molten tin and then through a body of palm oil, all of which are retained in a suitable vessel or apparatus known as a tin pot.

After the sheets are removed from the palm oil the excess oil is removed from their surfaces ofwashing, wiping or scouring with bran or by any-other suitable means.

The oil removed from the sheets or plates is not suitable for re-use, due to the fact that it is mixed with tar and pitch formed by the scorching or burning of the oil by the hot tin and sheets or plates. Small amounts of other foreign matter and metallic tin are also mixed with the oil. The oil remaining in the tin pots after excessive use also includes a mixture of tar, pitch and other foreign matter.

The present invention has for its object the recovery from used or refuse tin pot oil of the major portion, say fifty to eighty per cent. of the palm oil content in the form of commercially pure palm oil, having approximately the following characteristics Saponification number Notless than 190 Free acid value; Not more'than Calculated as palmitic 9 acid- Not morethan 18% U Iodine number 40 to Referring particularly to the accompanymg drawing, the method of this application will be described as carried out with the ap- The used palm oil, which is hot and which pot during the is heated sufficiently to render it fluid, is fed into a storage tank 2'through a conduit 3. This oil is then drawn from the tank 2 through a pipe 4 by a pump 5 and forced through a pipe 6 which extends through a. heat exchanger 7 to maintain the oil at the proper consistency. The pipe 6 delivers the oil to the upper end of an extraction tower 8. The required amount of solvent is supplied to the extraction still 9, or a part of the sol vent may be added to the oil in the tank 2 and the remainder may be supplied to the still 9. The still 9 is connected to the lower end of the extraction tower 8 by a pipe or conduit 10. p

- shown) for supplying the distillation heat.

The solvent supplied to the still 9 is vaporized by the heat in the still and the vapors pass up through the conduit 10 into the tower 8 where the flow is counter-current to the descending oil from the pipe 6. The solvent vapors are more or less absorbed by the descending palm oil, while any vapors which escape the oil pass from the tower 8 through a conduit 12 into a standard condenser 13 Where they are condensed and fiow back by gravity into the tower 8.

The temperature in the extraction tower 8 is regulated by the heat from the extraction still 9 and the heat supplied to the oil in the heat exchanger 7;

The oil and solvent mixture will flow from the tower 8' through a pipe 14 into a separating tank 15 where the heavy pitch containing a small amount of the solvent. together with more or less of the oil, depending upon 'the'completeness of the extraction, will settle by gravity and form a lower layer, while the extracted oil and the major portion of the lated from the tank 2 until substantially all 'where they are condensed and flow back the oil is extracted therefrom.

The oil and solvent flowing from the tank 2 into the extraction still 9 is distilled to drive off the solvent, and the oil being of a non-volatile nature com ared with the solvent, will remain and e collected in the still 9.

After the point of highest efliciency has been reached in the extraction process, that is-after'all the oil has been extracted or separated from the pitch and tar that is commercially possible, the oil and what solvent still remains in the oil after the still 9 has acted thereon, is drawn from the still 9 through a pipe 19 by a 'pump 20 and forced through a pipe 21 to a palm oil still 22.

The palm oil still 22 will then act to distil off any solvent remaining in the oil, which solvent will pass in vapor form through the pipe 23 and conduit 12 to the condenser 13 into the tower 8 and separating tank 15. The pure oil remaining in the palm oil still after the solvent has been distilled off is then drained off through a pipe 24 for re-use.

The pitch remaining in the separating tank 15 after the oil has been extracted is adapted to be drained through a pipe 25 into the storage tank 2 where it is mixed with any pitch remaining in the tank 2. and all the pitch is then drawn from the tank 2 through the pipe 4 by the pump 5 and forced through the pipe 6 and a branch pipe 26 to a pitch still 27 where the solvent content is distilled off and passes through a conduit 28 to the condenser 13 where it is condensed and flows into the tower 8.

The pitch remaining in the pitch still 27 is then drained off through a pipe 29 and treated in any suitable manner to recover its tin content and. if desired. the pitch may be treated in such a manner that it may be recovered for use wherever pitch is usable.

The conduits or pipes 23 and 28 are provided with valves 30 and 31, respectively, adapted to be closed when the stills 22 and 27, respectively, are not in use.

A valve 32 is provided in the pipe 25 and is adapted to be closed except when draining the pitch from'the separating tank 15, and a valve 33 is provided in the branch pipe 26 and is adapted to be closed except when pitch is being forced into the still 27. I

A system of pressure equalizing connections 35 are provided between the tower 8 and separating tank 15.

The best solvents so far known that are usable to extract the commercially pure palm oil from used palm oil, are those that are somewhat similar in constitution to palm oil,-

and are oxygen containing compounds of the alcohol, ketone and ester type. As re resentative examples of solvents that may e used in extracting the palm oil, the following have been selected; an acetone-water mixture and a mixture of ethyl alcohol, ethyl acetate and water. These and other solvents and solvent mixtures of the above general class have been successfully used.

Excellent results have been obtained with a solvent composed of a mixture of acetone and 5 to 10 per cent. water by volume. With this mixture, recoveries of 78 to 80 per cent. of commercially pure or fresh palm oil have been obtained. A recovered palm oil from a typical run with the aqueous acetone solvent showed the following chemical characteristics:

Saponification number; 193 Free acid value 32 Calculated as palmitic acid 15 Ash 0.17 per cent.

A pitch was recovered during the same run of used oil whichcarried 18 to 19 per cent. ash, containing per cent. tin. In recovering the above oil, approximately equal amounts of the acetone-water solvent and the refuse tin pot oil were used. All of the solvent, except that lost by leakage or a small amount (0.1 per cent. or less) discharged with the recovered oil and pitch, remains in the system and is used for succeeding runs.

Since such is the case, the actual proportion of solvent to oil is not important and may vary materially. The time of extraction depends to a considerable extent upon eflicient contact between the oil and solvent vapor and the completeness of extraction desired. Since the rate of extraction decreases greatly as the removal of good oil becomes more complete, it is not efficient to continue the extraction beyond the point where 78 or 80 per cent. of the good oil is recovered.

Substantially the same results as those set forth above have resulted when using the ethyl alcohol, ethyl acetate and water solvent mixture having the following proportions:

Percent Ethyl alcohol 90 to 95 Ethyl acetate 4 to 5 Water 1 to 5 When using this last stated solvent, however, almost twice as much solvent is used as oil treated by weight, and the method is carried out at slightly higher temperatures.

While we have shown and described one specific embodiment of apparatus for carrying out our novel method, together with a certain specific series and sequence of method steps, it will be understood that we do not wish to be limited to either the specific apparatus or sequence of method steps, since various modifications may be made without departing from the scope of our invention, as defined in the appended claims.

We claim 1. The method of recovering commercially pure palm oil from hot refuse palm oil which has been used in a tin pot or the like which consists in causing a thorough contact between said hot refuse oil and a hot vaporized solvent which is of the alcohol, ketone or ester type, said contact between said hot refuse oil and said hot vaporized solvent causing a mixture of said solvent with said refuse oil so as to dissolve the oil from the tarry and foreign matters of the refuse oils, separating said refuse oil and solvent mixture in the form of a mixture of said solvent and palm oil and a mixture of solvent and tarry and foreign matters, and finally separating said solvent from said palm oil so as to recover commercially pure palm oil.

2. The method of recovering commercially pure palm oil from hot refuse palm oil which has been used in a tin pot or the like, which consists in causing a thorough contact between said hot refuse oil and a hot vaporized solvent which is of thealcohol, ketone or ester type, permitting said refuse oil and solvent mixture to stratify by gravity into two layers, one layer being composed of a mixture of palm 011 and solvent and the other layer being composed of a mixture of the solvent and tarry residue and foreign matter contained in the refuse oil, separating said layer of oil and solvent from said layer of solvent and tarry residue, and finally separating said solvent from said oil.

3. The method of recovering commercially pure palm oil from hot refuse palm oil which has been used in a tin pot or the like which consists in causing a thorough contact between said hot refuse oil and a hot vaporized solvent which is of the alcohol, ketone orester type, permitting said refuse oil and solvent mixture to stratify by gravity into two layers, one layer being composed of a mixture of palm oil and solvent and the other layer being composed of a mixture of the tarry residue and solvent, separating said layer of oil and solvent from said layer of residue and solvent, and distilling the mixtures from said separate layers to'separate the solvent from the oil and tarry residue respectively.

4. The method of recovering commercially pure palm oil from hot refuse palm oil which has been used in a tin pot or the like which consists in causing said hot. refuse oil to flow counter-current to a flow of hot vaporized solvent, which is of the alcohol, ketone or ester type, said solvent dissolving the palm oil content of said hot refuse oil from the tarry and foreign matters thereof, causing the refuse oil and solvent mixture to stratify forming two layers, one layer being composed of a mixture of palm oil and solvent and the other layer being composed of a mixture of the tarry residue and solvent, separating said layer of oil and solvent from said layer of residue and solvent, and then distilling said separate mixtures to separate the solvent from the oil and tarry resldue respectively.

5. The method of recovering commercially pure palm oil from hot refuse palm oil which has been used in a tin pot or the like which consists in causing said hot refuse oil to flow counter-current to a flow of hot vaporized solvent of the alcohol, ketone or ester type, said solvent dissolving the palm oil content of said hot refuse oil from the tarry and foreign matters thereof, causing the refuse oil and solvent mixture to stratify forming two layers, one layer being composed of a mixture of palm oil and solvent and the other layer being composed of a mixture of the tarry residue, solvent and oil, separating said layer of oil and solvent from said layer of tarry residue, solvent and oil, recirculating said tarry residue, solvent and oil mixture so as to cause it to flow counter-current to said hot vaporized solvent until substantially all the oil is extracted therefrom, and finally separating said solvent from said palm oil to recover commercially pure palm oil.

6. The method of recovering commercially pure palm oil from hot refuse palm oil which has been used in a tin pot or the like which consists in causing said hot refuse oil to flow counter-current to a flow of hot vaporized solvent of the alcohol, ketone or ester type, said solvent dissolving the palm oil content of said hot refuse oil from the tarry and foreign matters thereof, causing the refuse oil and solvent mixture to stratify forming two layers, one layer being composed of a mixture of palm oil and solvent, and the other layer being composed of a mixture of the tarry residue, solvent and oil, separating said layer of oil and solvent from said layer of tarry residue, solvent and oil, recirculating said tarry residue, solvent and oil mixture so as to cause it to flow counter-current to said hot vaporized solvent until substantially all the oil is extracted therefrom, and finally separating said solvent from said palm oil and said tarry residue, and returning said solvent for reuse and recovering commercially pure palm oil and pitch.

In testimony whereof, we have hereunto set our hands.

CLARKE T. HARDING. JOSHUA C. WHETZEL. 

